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Estimating basal tear osmolarity in normal and dry eye subjects
Catherine Willshire1, Roger J Buckley1, Anthony J Bron2
1Vision and Eye Research Unit, Anglia Ruskin University, Cambridge, UK.
Summary
Measuring tear osmolarity after evaporative suppression provides a better index of body hydration and a baseline for dry eye disease severity. This new method, Basal Tear Osmolarity (BTO), offers a more accurate assessment than traditional tear osmolarity measurements.
Area of Science:
- Ophthalmology
- Physiology
- Biomedical Science
Background:
- Tear osmolarity (tOsm) is a key indicator for dry eye disease (DED) severity and body hydration.
- Current methods compare DED tOsm to a general control population, which may lack individual relevance.
Purpose of the Study:
- To investigate a novel method for assessing body hydration and DED severity by measuring tOsm after evaporative suppression.
- To establish a more accurate and personalized baseline for DED assessment.
Main Methods:
- Recruited 8 normal and DED subjects.
- Measured tOsm under controlled humidity (45% RH) with eyes open and closed (Experiment 1).
- Measured tOsm during exposure to higher humidity (70% RH) to suppress evaporation (Experiment 2).
Main Results:
- Significant decrease in tOsm observed in both normal and DED subjects after lid closure (Experiment 1).
- A slight, significant decrease in tOsm was noted in the normal group's left eye after exposure to 70% RH (Experiment 2).
- Evaporative suppression led to a fall in tOsm, approaching plasma osmolarity levels.
Conclusions:
- Evaporative suppression effectively lowers tOsm, suggesting a more stable physiological state.
- The proposed Basal Tear Osmolarity (BTO) measurement can serve as a reliable index of plasma osmolarity and body hydration.
- BTO offers a personalized baseline for DED, improving the assessment of tear hyperosmolarity severity.
